Because I have a fundamental right to privacy, and encrypted communications are an appropriate way to fulfill that right. While that right can be suspended at times, such as if a person were the subject of a criminal investigation after reasonable suspicion, a blanket prohibition of secure communication is not justified.
People act differently when they are being watched. This is not a bad thing, and is not an accusation of immoral behavior. People are more likely to pick their nose while in private. People are also less likely to express morally correct but unpopular beliefs, such as supporting gay rights a few decades ago, if they believe that it will have negative social consequences. By having privacy, social movements can slowly grow over time.
People act differently when they are being watched. This is not a bad thing, and is not an accusation of immoral behavior. People are more likely to pick their nose while in private. People are also less likely to express morally correct but unpopular beliefs, such as supporting gay rights a few decades ago, if they believe that it will have negative social consequences. By having privacy, social movements can slowly grow over time.